iodata.formats.charmm module

CHARMM crd file format.

CHARMM coordinate files contain information about the location of each atom in Cartesian space. The format of the ASCII (CARD) CHARMM coordinate files is: Title line(s), number of atoms in file and the coordinate lines (one for each atom in the file).

The coordinate lines contain specific information about each atom. These have the following structure: Atom number (sequential), residue number (specified relative to first residue in the PSF), residue name, atom type, x-coordinate, y-coordinate, z-coordinate, segment identifier, residue identifier and a weighting array value.


Load a single frame from a CRD file.


lit (LineIterator) – The line iterator to read the data from.

Return type:



result (dict) – A dictionary with IOData attributes. The following attributes are guaranteed to be loaded: atcoords, atffparams, atmasses, extra. The following may be loaded if present in the file: title.